As conventional navigation apparatuses, there are widely known small-sized portable navigation apparatuses with simplified structure and portability (hereinafter, referred to as Portable Navi), also known as Personal Navigation Device; and vehicle-mounted navigation apparatuses accommodated and fixed in a recess portion (DIN opening) formed in a dashboard of a vehicle. The vehicle-mounted navigation apparatuses are capable of guiding with high accuracy by use of the information supplied from vehicles such as vehicle speed, and some of the vehicle-mounted navigation apparatuses are equipped with audio devices.
In recent years, the navigation apparatuses with portability of the Portable Navi and high-accuracy guide function of the in-vehicle navigation apparatus have been studied.
References 1 to 4 disclose a configuration where a navigation portion can be attached and detached to/from an in-vehicle apparatus mounted in a vehicle. By removing the navigation portion from the in-vehicle apparatus, the navigation portion can be used as a Portable Navi of a single unit.
Also, as disclosed in Reference 5, the navigation apparatus is taken out of the vehicle and can be used while walking. In addition, when mounted in a vehicle, the navigation apparatus is in a car-navigation mode, and when taken out of the vehicle, the navigation apparatus is in a person-navigation mode.    [Reference 1] Japanese Unexamined Patent Publication No. 8-318792    [Reference 2] Japanese Unexamined Patent Publication No. 2002-328026    [Reference 3] Japanese Unexamined Patent Publication No. 2005-524570    [Reference 4] Japanese Unexamined Patent Publication No. 2001-239895    [Reference 5] Japanese Unexamined Patent Publication No. 2003-166848